L6 - Glycolysis

Catabolism is the _____ phase of metabolism and _____ energy

degrative; releases

Anabolism (biosynthesis) is the ____ phase of metabolism and _____ energy

building; requires

_______ is the crossroad between catabolic and anabolic pathways

Acetate (Acetyl-CoA)

In the first step of glycolysis, the phosphorylation of glucose

traps glucose in the cell. ATP is a phosphoryl donor. Irreversible; Creates Glucose 6-phosphate

Hexokinase and Glucokinase

All phosphorylates glucose; Hexokinase is in all cells but glucokinase is only in liver calls

Glucose and fructose are

isomers

Reaction coupling

A thermodynamically unfavorable reaction can be driven in the forward direction by coupling it to a highly exergonic reaction

Substrate level phosphorylation - ATP formed by direct transfer of a phosphoryl group from a high energy compound to

ADP

Net ATP made from glycolysis

2

Total ATP made from glycolysis

4

Steps of the preparatory phase of glycolysis (1-5); Which is and isn’t reversible

1. Phosphorylation of Glucose to Glucose 6-phosphate (G6P) via hexokinase (Needs ATP and Mg²⁺); Irreversible

2. Phosphohexose isomerase (Needs Mg²⁺) opens the G6P and turns it into Fructose 6-phosphate (F6P); Reversible

3. F6P is converted into Fructose 1,6-bisphosphate (F16BP) via phosphofructokinase-1 (PFK-1) (Needs ATP and Mg²⁺); “commitment step” glycolysis MUST continue from this point; rate-limiting; irreversible

4. F16BP is cleaved via aldolase to create Dihydroxyacetone phosphate (DHAP) and Glyceraldehyde 3-phosphate (GA3P); Reversible

5. DHAP is converted to GA3P via triose phosphate isomerase; reversible

You end up with two GA3P

Steps of the payoff stage of glycolysis (6-10)

Remember: Each step results in two products for every one input of _D-glucose (Basically, the steps happen twice)

6. GA3P + inorganic phosphate (HPO₄^-2) makes 1,3-Bisphosphoglycerate (13-BPG) via glyceraldehyde 3-phosphate dehydrogenase (GAPDH). A reduction reaction that uses NAD⁺ (Converted to NADH + H⁺). Note: This reaction does not use ATP like the other phosphorylation reactions previously in this pathway.

7. 12-BPG is used to phosphorilate ADP via phosphoglycerate kinase (Needs Mg²⁺), which creates 3-Phosphoglycerate (3PG) and ATP

8. 3PG is converted into 2-phosphoglycerate (2PG) via phosphoglycerate mutase (Needs Mg²⁺)

9. 2PG is converted to phosphoenolpyruvate (PEP) via enolase (Dehydration reaction)

10. PEP is used to phosphorylate ADP via pyruvate kinase (Needs Mg²⁺ and K⁺), which creates pyruvate and ATP; Irreversible

Mnemonic for Glycolysis Products

Gross - glucose

Guys - glucose-6-phosphate

Favor - fructose-6-phosphate

Fat Butts - fructose-1,6-bisphosphate

Good - glyceraldehyde-3-phosphate

Boys - 1,3-bisphosphoglycerate

Prefer - 3-phosphoglycerate

Pretty - 2-phosphoglycerate

Pink - phosphoenol pyruvate

Pussies - pyruvate

Mnemonic for Glycolysis Enzymes

Honestly: Hexokinase

Ignoring: Isomerase (Phosphohexose)

Penis: Phosphofructokinase-1

And: Adolase

Instead: Isomerase (Triose phosphate)

Getting: Glyceraldehyde 3-phosphate dehydrogenase

Pussy: Phosphoglycerate Kinase

Makes: Mutase

Everything: Enolase

Perfect: Pyruvate Kinase

Substrate level phosphorylation

A direct metabolic reaction that produces ATP (or GTP) by transferring a high-energy phosphate group from a phosphorylated intermediate molecule (High phosphoryl group transfer potential) to ADP

Mutase enzyme

Catalyzes the movement of one functional group to another spot on the same molecule

Net equation of glycolysis

Glucose + 2 NAD⁺ + 2 ADP + 2 P_i → 2 Pyruvate + 2 NADH + 2 H⁺ + 2 ATP + 2 H₂O